1. Field of the Invention
The present invention relates to, for example, a data relay processing method for determining allocations or the like of transmission bands in networks, a data relay processing unit and a program recording medium.
The present invention also relates to an information drop method and an information drop unit for selecting important information to be transmitted.
2. Related Art of the Invention
In the Internet a protocol (for example a protocol called RSVP) for making a band reservation has been proposed conventionally, but route control according to QoS (transmission quality) hasn't been considered. That is to say in the present Internet transmission quality such as transmission bands, delays and jitters are reserved in advance and transmission resources are reserved on a predetermined transmission route.
Therefore, in the case that there are extra transmission bands of a network, the resources of the whole network cannot be uses effectively with some cases where unused routes exist. To solve this problem a system where QoS routing (route control) is available has been proposed conventionally.
For example, “QoS routing unit” (Japanese patent application H7(1995)-315558) by Atsushi Iwata can be cited. According to the conventional system, transmission bands, delays, jitters or the like are defined as QoS and a routing unit is proposed which is able to search routes satisfying the requirements of QoS that are expected to be satisfied in sequence.
In the above described conventional system, however, the following problems (1) and (2) are cited.
That is to say problem (1): the conventional system is a method for reserving in advance fixed transmission bands (for example, a band of 20 Mbps) at the time of transmission resource reservation. Namely, for example, at the time a transmission band of 20 Mbps is reserved, even in the case that it is understood in advance that a used band of 10 Mbps is going to decrease after a certain period of time, transmission by the band of 20 Mbps which has been used so far is stopped once and transmission is carried out by newly reserving a band of 10 Mbps after said certain period of time.
This is because there is no method for reflecting the usage plan or the usage record of the network resources by other users, and even in the case where there are scheduled to be, or tend to be, extra network resources those extra network resources will not be used, therefore, efficiency of the usage of the whole of the network resources cannot be expected to improve.
Problem (2): in the case that a plurality of transmission resources are selectable at the time of transmission resource reservation, it used to be difficult to improve the usage effectiveness of the transmission route while controlling the setting of the communication price because there was no such thing as a reference based on the idea that the communication price is adjusted among resources where the reservation of the transmission resources are available. When searching a route, even if the load of the terminal carrying out relay processing of data is high, a large amount of time is spent for data relay processing in the case that a relay terminal with a high load is selected as a search object because there is a possibility it maybe selected as an object of a search of data relay processing.
On the other hand, a system for controlling traffic amount by performing packet drop according to the load of the network following the priority attached to the Internet protocol packet has been proposed conventionally (IETF: Internet Engineering Task Force, RFC2597, RFC2598).
In this conventional system, however, said priority is determined by judging whether the contents are important or not based on the type of streams such as image signals or speech signals, or control signals (Microsoft Inc.: ASF; Advanced Streaming Format).
Accordingly, in the conventional system, there's a problem (3) that the processing lacks flexibility because only the types of streams are focused on.
For example, a method for making the importance level to the terminals, to the types of image or speech frames (I, P, B) or to set unit of those frames in a certain range (for example GOB: Group Of Block in MPEG1) correspond to the Internet protocol packets is not set therefore there is a problem (3) that more important information cannot be selected flexibly to be transmitted by giving a higher priority to each terminal important image frame or speech part.